Floor Temperature

A remote infrared thermometer will do that. Often sold as a "laser" thermometer as commercial hand-held units, but most likely available as a module, or could be hacked if not.

Dave.

Least bad cheap solution I can see is a plastic LCD based thermometer in the right temp range and a colour webcam to monitor it. Risk is there may be other colder spots on the floor if you cut it too fine.

I doubt if anything else is under your budget.

Shame you can't measure either the resistance or working fluid exit temperature of the under floor heating pipes.

Regards, Martin Brown

Would a contactless IR sensing thermometer work?

So reliable readings are not likely off a concrete floor in a busy garage.

And also forget coming here with crackpot ideas and specifying an absurd budget.

..... Phil

Ok, Phil,

How would you do it budget or not? An IR sensor and PIC would fall the price range. Lets be constuctive here.

BobS

One simple approach would be to put a small phase change sensor on the floor--e.g. a tuna fish can half full of water, with a piece of glass epoxied on as a lid and some sort of disinfectant to keep it from going too scummy.

A chopped LED/photodiode reflective sensor will detect the light scatter when it freezes. No calibration required--but don't use salt for the disinfectant. ;)

Cheers,

Phil Hobbs

Anti-freeze.

But couldn't you simply use one of those IR thermometers and monitor the floor temperature?

...Jim Thompson

By the time it freezes you'll probably have the first fender benders already.

Bob: Why can't you embed a regular NTC somewhere off the usual vehicle paths? Must be in a place where there are no heater lines. Drill a hole into the concrete and pot it up really well. Chisel a trench from there to the wall.

Best would be if this was a stainless encapsulated version or similar with the top exposed so it catches a freeze early enough. Then figure out via a test at which temperature you'd want the heaters to come on.

You could also mount it really low on a wall but if this garage or whatever it is could be visited by the graffiti gang that might be vandalized.

Small amount is all it takes to disinfect ;-)

...Jim Thompson

(see smiley below)

Sure. To within a few degrees, that should work OK, assuming the emissivity of the floor is known accurately enough. Concrete's is quite reasonable, though it matters whether it's wet. the OP can also just glue a sensor to the concrete, as long as he thermally grounds the wires as well. Thermal grounding could be as simple as gluing the wires to the floor for a length equivalent to 1000-2000 wire diameters. It's necessary because the thermal conductivity of copper is about 300-400 W/m/k, which is thousands of times higher than that of the insulation and the glue, so almost all the heat will actually go in and out of the sensor by way of the wires.

It's very very common for people's temperature sensors to be really measuring the temperature of a circuit board several feet from the sensor.

Phase change sensors have the disadvantage that they aren't very settable, and the advantage that they don't need calibration.

To the OP: How about just putting some propylene glycol in your heating loop? Noncorrosive, nontoxic, no freezing worries.

Cheers,

Phil Hobbs

How is the floor heat accomplished? Electric coil? Heated liquid (glycol,water,whatever..)?

D from BC British Columbia Canada

Brings to mind... if it's a fluid circulated in a pipe, why not begin circulating the fluid when the outside air temperature drops below freezing, monitor fluid temperature and apply heat accordingly?

...Jim Thompson

How would you do it budget or not?

Connect it to a K-thermocouple amplifier and use the output voltage to do the job.

Interfacing is your problem - pal.

...... Phil

"Phil Hobbs"

To a HP 400A true rms voltmeter ???

... Phil

"Paul Hovnanian P.E."

.... Phil

I think your money would be best spent figuring out how to encapsulate a contact-type sensor to protect it from ambient gunk.

I just sent you an email that may be of interest, based on your location.

Ed

Have you tried a builder's stud-locator to map conductor locations?

These are often sensitive to live conductors, as well (apply power when searching).

This could give you a safe sensor/wire routing option.

I frankly don't see the point of heating a garage floor, when used only for vehicular storage. What is the aim here - to protect the heating system from damage?

RL

"legg"

..... Phil